278 PBACTIGAL BOTANY. 



the decurrent base of the lobed and toothed, somewhat prick- 

 ly leaves. Heads large ; involucral scales spiny. 



Onopordon Acanthium, L. 

 Receptacle not honeycombed 940 



940. Involucral scales hooked. Leaves large, petioled, 

 upper ones ovate, the lower heart-shaped. Heads solitary, or 

 clustered ; flowers purplish. Lappa Major, Gaertn. 



{Burdock.) 

 Involucral scales not hooked 941 



941. Pappus threefold — namely, 10 short, horny teeth, 10 

 slender, rigid bristles, and as many shorter ones. Flowers 

 yellow. Cnicus benedictus, L. 



Pappus of one sort ; its bristles united at the base 

 in a ring. Leaves sinuate, or piunatifid, spiny, usually decur- 

 rent. Flowers purplish 942 



942. Pappus plumose. Girsium. 

 Pappus capillary. Heads solitary, dropping. 



Carduus nutans, L. 



943. (905.) Receptacle chafiy — that is, with pales among 

 the flowers 964 



Receptacle naked, or deeply honeycombed 944 



944. Receptable deeply honeycombed. Heads solitary, 

 globular, at the summit of each stem. Rays neutral, long, 

 narrowly wedge-shaped, yellow ; disk-flowers at length pur- 

 ple. Receptacle strongly convex. Achenia silky-villous. 

 3Pappus of 7-9 oblong-lanceolate chafiy scales. Leaves ob- 

 lanceolafe. Bald'winia uniflora, Nutt. 



Receptacle not honeycombed 945 



945. Pappus of 5-12 scales, or of many capillary bristles 



946 



Pappus none, or of a few short awns or a crown. 



Leaves alternate 961 



946. Pappus of 5-12 scales 947 



Pappus of many capillary bristles 949 



947. Leaves alternate 948 



Leaves opposite. Pappus-scales deeply cleft into 

 capillary bristles. Leaves dotted, pinnately parted into nar- 



